Hi guys, I'm not very expert with arduino and with programming in general; I make a CPS (Concented Solar Power) for my thesis ( i'm becoming a mechanical engineer) and i'm trying to develope an automated system for the Solar Traking and for putting temperature data online on a chart. Every thing works pretty well, but I'd love to split the code in come .h and .cpp files to make it more "professional". So I splitted the loop in a few functions(FS,SC,PrintTime), but i'm getting this issue: sketch\FS.cpp.o:(.bss.display+0x0): multiple definition of `display' sketch\Controller.ino.cpp.o:(.bss.display+0x0): first defined here sketch\PrintTime.cpp.o:(.bss.display+0x0): multiple definition of `display' sketch\Controller.ino.cpp.o:(.bss.display+0x0): first defined here sketch\SC.cpp.o:(.bss.display+0x0): multiple definition of `display' sketch\Controller.ino.cpp.o:(.bss.display+0x0): first defined here collect2.exe: error: ld returned 1 exit status I Think the problem in related to: all the function print something on the display (SSD1306). I created a .h file with all the delarations for that display, then i included it in every .cpp files. I have tried lot of thing, i cannot understand why it says there are multiple definition. Could someone help me please? Thanks in advance guys, RIccardo.

[image] ricca30: OK so what I did it's basically good..I'll try to put all the include on the cpp... don't know what this means [image] ricca30: extern Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); the above, the definition/constructor is needed in the .cpp file [image] gcjr: extern Adafruit_SSD1306 display; the above declaration is needed in the .h file so that the compiler knows about display in .ino/.cpp files referencing it.

"Concented" Concentric? Concentrated? Error code, but no code == no help

Without seeing your complete code it is difficult to provide any help so please post your sketch and library files Please post your code following the advice given in the link below [image] How to get the best out of this forum IDE 1.x See also FAQ - Arduino Forum for general rules on forum behaviour and etiquette. Hello, Welcome to the Arduino Forum. This guide explains how to get the best out of this forum. Please read and follow the instructions below. Being new here you might think this is having rules for the sake of rules, but that is not the case. If you don’t follow the guidelines all that happens is there is a long exchange of posts while we try to get you to tell us what we need in order to help you, which is fru…

[image] ricca30: delarations [sic] for that display, Read the error messages, then be sure you are repeating the declarations, not the definitions of all those things it’s complaining about. a7

Are you maybe missing the "extern" keyword?

Thank guys, I miss a few things like the code to put data on web( already tested alone) And 2 temperature sensor. l'll try to share the code.. Main one #include "PINOUT.h" #include "FS.h" #include "SC.h" #include "PrintTime.h" boolean FS = true ; const char* ntpServer = "pool.ntp.org"; const long gmtOffset_sec = 3600; const int daylightOffset_sec = 3600; //////time///////// const char* ssid = "TP-LINK_A7650E"; const char* password = "*************"; ////////////////////////// void setup() { Serial.begin(115200); pinMode ( LS1, INPUT ); pinMode ( LS2, INPUT ); pinMode ( LS3, INPUT ); pinMode ( LS4, INPUT ); pinMode ( MTC, OUTPUT ); pinMode ( MTA, OUTPUT ); pinMode ( MPA, OUTPUT ); pinMode ( MPO, OUTPUT ); pinMode ( SMAXTILT, INPUT ); pinMode ( SMINTILT, INPUT ); pinMode ( SMAXPAN , INPUT ); pinMode ( SMINPAN, INPUT ); digitalWrite ( MTC, HIGH); digitalWrite ( MTA, HIGH); digitalWrite ( MPA, HIGH); digitalWrite ( MPO, HIGH); /////OLED_I2C/////// display.begin(SSD1306_SWITCHCAPVCC, 0x3C); //connect to WiFi Serial.printf("Connecting to %s ", ssid); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(" CONNECTED"); //init and get the time configTime(gmtOffset_sec, daylightOffset_sec, ntpServer); printLocalTime(); } void loop() { if ( FS == true){FirstStart(); FS = false; } ////FIRST START SolarCheck(); } FS.ccp (first start = open to max) #include "FS.h" void FirstStart(){ Serial.println ("1st start"); Serial.println ("tilt"); display.clearDisplay(); display.setCursor(0, 0); display.println("First Start Adj.."); display.display(); display.print("Tilt Axis.."); display.display(); while (digitalRead(SMAXTILT) == 1){ digitalWrite(MTA, LOW);} digitalWrite(MTA, HIGH); Serial.println ("tilt max"); display.println("Tilt Max!"); display.println("Pan Axis..."); display.display(); Serial.println ("pan"); while (digitalRead(SMAXPAN) == 1){digitalWrite(MPA, LOW);} digitalWrite(MPA, HIGH); Serial.println ("pan max"); display.print("Pan Max!"); display.display(); display.clearDisplay(); delay(2000); } FS.h #ifndef FS_H #define FS_H #include "PINOUT.h" #include "displaydef.h" void FirstStart(); #endif SC.cpp (Solar Check) ///////////////////////////////////// /////////SOLAR CHECK//////////////// //////////////////////////////////// #include "SC.h" #include "FS.h" unsigned long t1, dt; // X SOLARCHECK void SolarCheck(){ int LS1Val = analogRead(LS1); int LS2Val = analogRead(LS2); int LS3Val = analogRead(LS3); int LS4Val = analogRead(LS4); dt= millis() - t1; if(dt >= 5000) { t1=millis(); Serial.println("Solar Check"); display.clearDisplay(); display.setCursor(0,0); display.println("Solar Check"); display.println(""); Serial.print("SX: "); Serial.println(LS1Val); display.setCursor(0,16); display.print("Sx: "); display.println(LS1Val); if ( LS1Val > 600 & LS1Val > (LS2Val*1.2) ) {digitalWrite ( MPO , LOW); delay(500);digitalWrite ( MPO , HIGH);} else {digitalWrite ( MPO , HIGH);} Serial.print("DX: "); Serial.println(LS2Val); display.print("Dx: "); display.println(LS2Val); if ( LS2Val > 600 & LS2Val > (LS1Val*1.2) ) {digitalWrite ( MPA , LOW);delay(500);digitalWrite ( MPA , HIGH);} else {digitalWrite ( MPA , HIGH);} Serial.print("UP: "); Serial.println(LS3Val); display.print("UP: "); display.println(LS3Val); if ( LS3Val > 600 & LS3Val > (LS4Val*1.2) ) {digitalWrite ( MTA , LOW); delay(500);digitalWrite ( MTA , HIGH);} else {digitalWrite ( MTA , HIGH);} Serial.print("DOWN: "); Serial.println(LS4Val); display.print("Down: "); display.println(LS4Val); if ( LS4Val > 600 & LS4Val > (LS3Val*1.2) ) {digitalWrite ( MTC , LOW); delay(500);digitalWrite ( MTC , HIGH);} else {digitalWrite ( MTC , HIGH);} display.display(); display.clearDisplay(); } if (digitalRead(SMINPAN) == 0 & LS1Val > 200){ Serial.print ("RO Pan.."); display.setCursor(0,0); display.print("RO Pan.."); display.display(); while(digitalRead(SMAXPAN) == 1){digitalWrite(MPA, LOW);} Serial.print ("Max Pan!"); display.println("Max Pan"); display.display(); display.clearDisplay();} ///REOPEN if (digitalRead(SMINTILT) == 0 & LS1Val > 200){ Serial.print ("RO Tilt.."); display.setCursor(0,0); display.print("RO Tilt.."); display.display(); while(digitalRead(SMAXTILT) == 1){digitalWrite(MTA, LOW);} Serial.print ("Max Tilt!"); display.println("Max Tilt"); display.display(); display.clearDisplay();} ///REOPEN delay(100); } SC.h #ifndef SC_H #define SC_H #include "PINOUT.h" void SolarCheck(); #endif displaydef.h ( i made this to just define all i need for display print one time) #ifndef displaydef_H #define displaydef_H #include #include #include #include #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels #define SCREEN_ADDRESS 0x3C Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); #endif PINOUT.h (i don't now if it's good or it's better to keep it in main) #ifndef PINOUT_h #define PUNOUT_H ///////input/////// ///luxmeters// #define LS1 33 //sx #define LS2 32 //dx #define LS3 34 //up #define LS4 35 //down ///microswitch #define SMAXTILT 15 #define SMINTILT 2 #define SMAXPAN 4 #define SMINPAN 0 ////output////// ///MOTORS #define MTC 18 //Tilt Chiudere #define MTA 5 //Tilt Aprire #define MPA 16 //Pan AntiORario #define MPO 17 //Pan Orario #endif Print time.h ( printlocaltime() is just an example copyed from esp time library) #ifndef PrintTime_H #define PrintTime_H #include "time.h" #include //#include "displaydef.h" void printLocalTime(); #endif

[image] ricca30: Concented Solar Power Concentrated.. Sorry wrote it so fast..

Yep sorry, it was Definition not declaration sketch\FS.cpp.o:(.bss.display+0x0): multiple definition of `display' sketch\Controller.ino.cpp.o:(.bss.display+0x0): first defined here sketch\PrintTime.cpp.o:(.bss.display+0x0): multiple definition of `display' sketch\Controller.ino.cpp.o:(.bss.display+0x0): first defined here sketch\SC.cpp.o:(.bss.display+0x0): multiple definition of `display' sketch\Controller.ino.cpp.o:(.bss.display+0x0): first defined here collect2.exe: error: ld returned 1 exit status

[image] anon73444976: extern Have I to write it? where?

[image] ricca30: Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); the above in displaydef.h causes display to be defined in every .ino/.cpp file displaydef.h is included in i think display can be defined as an extern in the .h extern Adafruit_SSD1306 display;

First try with .h and .cpp, Multiple Definition issue

Projects Programming

UKHeliBob May 15, 2021, 11:31am 3

Without seeing your complete code it is difficult to provide any help so please post your sketch and library files

Please post your code following the advice given in the link below

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First try with .h and .cpp, Multiple Definition issue

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